Air balancer safety system

ABSTRACT

A balancing hoist control system including a pressure regulator valve and having a check valve located between the main air supply and the main inlet of the regulator valve and operative to close in response to a failure in the air supply, thereby preventing the air in the hoist from escaping from the main inlet. An air-operated piston member disables the regulator in the event of the loss of pressure of the air supply to prevent the regulator valve from exhausting the main balancing chamber of the hoist. This piston member also interconnects the main air supply chamber of the regulator valve with the pilot air chamber so that an operator can use the control member to slowly lower the load after the failure of the air supply without waiting for the repair of the air supply.

United States Patent Ulbing 51 Jan. 18, 1972 [54] AIR BALANCER SAFETY SYSTEM Primary Examiner-Ev0n C. Blunk Assistant Examiner-Merle F. Maffei [72] Inventor. Otmar M. Ulbing, Berkshire, N.Y. Anomey cafl R. Hone" and David w. Tibbon [73] Assignee: Ingersoll-Rand Company, New York, NY. 221 Filed: Oct. 8, 1969 [57] ABSTRACT A balancing hoist control system including a pressure regula- [21] Appl' 864332 tor valve and having a check valve located between the main air supply and the main inlet of the regulator valve and opera- [52] US. Cl ..254/l68, 254/ l 86, l37/505 l8 ti e to close in response to a failure in the air supply, thereby 1/08 preventing the air in the hoist from escaping from the main in- [58] Field of Search ..254/l68, l86; 137/505.l8 let An aipoperated piston membfl disables the regulator in the event of the loss of pressure of the air supply to prevent the [56] References and regulator valve from exhausting the main balancing chamber UNITED STATES PATENTS of the hoist. This piston member also interconnects the main air supply chamber of the regulator valve with the pilot air 3,325,148 6/1967 POWGll X chamber 50 that an operator can use the control member to 3,457,837 7/1969 Powell 354/186 X slowly lower the load after the failure of the air supply without 3,485,259 12/1969 Ulbmg 1 37/505. 1 8 waiting f the repair f h i Supply 2,940,462 6/1960 Johanson ..137/508 AIR SUPPLY 3 4 Claims, 2 Drawing Figures PATENTED JAN] 8 m2 3.535442 AIR SUPPLY 39 FIG. I

25 FIG. 2

INVENTOR OTMAR M. UL B/NG BY BMW. \MQW ATTORNEY AIR BALANCER SAFETY SYSTEM BACKGROUND OF INVENTION This invention relates to a control system and mechanism for operating and controlling a balancing hoist containing a fluid pressure operated member for balancing a load supported by the hoist. A hoist of this general type is disclosed in my U.S. Pat. No. 3,421,737, granted Jan. 14, 1969.

Conventional balancing hoists controlled by pilot-operated regulator valves may suddenly drop a load if their air supply fails, such as might be caused by a breakage or cutting of the airhose supplying the balancer. As a result, such a balancer is dangerous to both the operator and anyone working nearby. One solution to this problem is to locate a pilot-operated check valve between the regulator valve and the main chamber of the hoist. Although this expedient keeps the hoist from dropping its load upon the failure of the air supply, the operator cannot thereafter lower the load until the air supply is again fixed.

SUMMARY OF INVENTION The principal object of this invention is to provide a novel balancing hoist control system which overcomes the above danger provided by the conventional balancing hoist control system.

Other important objects of this invention are: to provide a novel control system for a balancing hoistincluding a pressure-operated member for disabling a pilot-operated regulator valve in the event of .a sudden loss in pressure of the main air supply for the hoist; to provide an automatically operated valve for interconnecting the main air chamber of the balancing hoist with the pilot pressure control system in the event of a loss in the main air supply pressure whereby the pilot control system can be utilized for slowly lowering the load in the balanced balancing hoist; and to provide an improved control system for a balancing hoist.

In general, the foregoing objects are obtained in a control system including an air supply, a pilot-operated regulator valve having a main inlet connected to the air supply, a main outlet connected to the hoist member for supplying the hoist member with a controlled air pressure, a pilot port adapted to receive a pilot air pressure for controlling the regulator valve and causing it to supply air pressure to the hoist member in response to the pilot air pressure and a control member connected to the air supply and to the pilot port to supply the pilot port with a variable pilot air pressure. A check valve is located between the main inlet in the regulator valve and the air supply and is operative, in response to a drop in pressure of said air supply, to seal the main inlet from the air supply. A member is operative, in response to a drop in pressure in the air supply, to prevent the regulator valve from exhausting pressure from its main outlet. The control system further includes a valve means which is operative, in response to a drop in pressure of the air supply, to interconnect the main outlet to the pilot port so that the operator can use the control member for bleeding pressure from the hoist member at a controlled rate to slowly lower the load in the hoist.

BRIEF DESCRIPTION OF DRAWING The invention is described in connection with the accompanying drawings wherein:

FIG. 1 is a combination schematic view and fragmentary sectional view of the control system of the invention with the regulator valve and surrounding portions shown in section; and

FIG. 2 is an enlarged fragmentary view of the sectional portion of FIG. 1 showing the air-operated piston in an alternate position wherein the regulator valve is prevented from its normal operation.

DESCRIPTION OF PREFERRED EMBODIMENT The balancing hoist 1 schematically shown in FIG. I includes an outer casing 2 which may be supported on a suitable overhead support, a hoist drum 3 contained in the casing 2 and mounted to rotate and simultaneously reciprocate therein in a controlled manner, and a hoisting cable 4 wound around the drum 3 with the portion depending from the drum and connected to a suitable load 5. The drum 3 is controlled by an air chamber 6 formed in the hoist. Air pressure in the chamber 6 opposes the weight of the load 5. A lbalancing hoist of this type is conventional and is fully described in my U.S. Pat. No. 3,421,737, and, therefore, is not further described in this application.

The air chamber 6 is connected by the passage 7 to the main outlet 8 of a pilot-operated regulator valve 9 which is shown in section in FIGS. 1 and 2. The regulator valve 9 includes a housing 10 which normally is attached to the casing 2 of the hoist 1. The regulator valve 9 further includes a main inlet and a pilot port 12. The regulator valve 9 also includes a main outlet chamber 14, an air supply chamber 115, and a pilot air chamber 16. Each of these chambers is separated from the others by a pair of diaphragms 21 and 22.

The first diagram 21 separates the main air outlet chamber 14 from the air supply chamber 1.5, while the second diaphragm 22 separates the air supply chamber 15 from the pilot air chamber 16. The main air outlet chamber 14 communicates with the main air supply chamber 15 through a supply valve opening 23. In addition the main outlet chamber 14 communicates with the atmosphere through an exhaust valve opening 24. The supply valve opening 23 is mounted on a movable valve member 25 which is supported on the housing I0 of the regulator valve 9 by the respective first and second diaphragms 21 and 22. The valve member 25 is free to move up and down in response to air pressures acting on the diaphragms 21 and 22. The valve member 25 further carries a valve plug 26 which is movably mounted on the valve member 25 by a smaller diaphragm 27. The valve plug 26 is adapted to seat on the seats of both the supply valve opening 23 and the exhaust valve opening 24. As shown in FIG. 1, the valve plug 26 is seated on and closing both the valve openings 23 and 24.

If the air pressure in the pilot air chamber 16 overcomes the air pressure in the main air outlet chamber R4 the valve member 26 moves downwardly relative to the positions as shown in FIG. 1 to open the supply valve opening 23, so air pressure in the main air supply can flow into the main air outlet chamber 14, as shown in FIG. 2. Conversely, if the pilot air pressure in the chamber 16 is reduced below the air pressure in the main air outlet chamber 14 the valve member 25 moves upwardly, relative to the position shown in FIG. l, to lift the valve plug 26 off of the seat of the exhaust valve opening 24, thereby exhausting the air pressure in the main air outlet chamber 14 to atmosphere. This type of regulator valve is shown and described in my U.S. Patent application, Ser. No. 655,439, filed July 24, 1967, now U.S. Pat. No. 3,485,259.

The schematic diagram in FIG. 1 further contains an air supply 30 supplying air through a main air pipe 31. Air pressure is supplied from the main inlet 11 to a smaller air line 32 which contains an adjustable throttle valve 33 for throttling and reducing the air pressure flowing through the line 32. The pilot air line 32 connects to the pilot port 12 of the regulator valve 9 and also to a control member 35. The control member 35 vents or exhausts the air pressure at the pilot port 12 at a controlled pressure to maintain the pilot pressure in the pilot air chamber 16 at a predetermined selected value. The control member is adjusted by the operator to provide the desired pilot pressure. A control member for accomplishing this job is shown and described in my aforementioned U.S. Pat. No. 3,421,737.

A spring-operated check valve 37 is located between the main air pipe 31 and the main inlet 11. The check valve 37 allows the air supply to flow forwardly into the main inlet 11 but automatically prevents a counterflow of air from the main inlet 11 to the main air pipe 31. The check valve 37 includes a conventional check ball, also designated 37, and a spring 38 urging the check ball 37 against a seat.

The housing further includes a piston 40 having a front face 41 subject to the pressure in the main air pipe 31 and a rear face 42 subject to the air pressure in the main inlet 11. A passage 43 extends between the rear face 42 of the piston 40 and the main inlet 11. When the air supply 30 is supplying normal pressure to the main air pipe 31 the piston 40 remains in the position shown in FIG. 1 due to the pressure acting on its front face 41 being slightly higher than the pressure acting on its rear face 42, caused by a pressure drop occuring across the check valve 37. However, if and when the pressure in the main air pipe 31 fails and the check valve 37 closes, the differential pressure across the piston immediately is higher on the piston rear face 42 and, as a result, moves it forward toward the regulator valve 9.

The piston 40 carries a plunger 45 which extends through a bore 46 and terminates in a shoe 47. The shoe 47 is adapted to engage the rear of the regulator valve 9 as shown in FIG. 2

when the air supply 30 fails. In the FIG. 2 position, the shoe 47 holds the regulator valve 9 from moving through its normal operation. Also in the FIG. 2 position, the supply valve opening 23 is open and the exhaust valve opening 24 is closed. This prevents the regulator valve-from opening the exhaust valve opening 24 to exhaust the pressure from the main outlet chamber 14, which otherwise would occur if the pressure of the air supply 30 failed suddenly, while the air supply chamber communicates with the main outlet chamber 14.

The valve plunger 45 also forms a valve which connects the main inlet 11 to the pilot air chamber 16 if and when the air 1 supply pressure fails. The main inlet 11 connects to a passage 48 which extends into a valve cavity 49 in the bore 46 surrounding a reduced portion 50 of the plunger 45. The plunger carries O-rings 51 located on the opposite sides of the cavity 49 so as to seal the cavity 49 from the pilot air chamber 16 when the plunger 45 is in its inoperative position, shown in FIG. 1. When the plunger 45.moves forwardly against the regulator valve 9, as shown in FIG. 2, its reduced portion moves into the pilot air chamber 16 to open the cavity 49 into the pilot air chamber 16. The air pressure in the main inlet 11 flows into the pilot air chamber 16 to act on the rear of the regulator valve 9 to aid the shoe 47 in holding the regulator valve in its nonoperative position, as shown in FIG. 2.

As a result of interconnecting the main inlet 11 with the pilot air chamber 16, an operator can bleed pressure from the main outlet chamber 14 at a controlled rate so that a load 5 on the hoist can be slowly lowered even though the pressure of the air supply has failed. In previous safety systems for this type of hoist for preventing the dropping of the load upon the failure of the air supply, it was impossible to move the hoist until the air supply was again fixed. In this invention the operator can immediately remove the load from the hoist before attempting to repair the failure of the air supply. Hence the operator can thereafter work on the hoist without fear of the load dropping while fixing the air supply.

Although a single embodiment of the invention is illustrated and described in detail, it should be understood that the invention is not limited merely to this embodiment, but contemplates other embodiments and variations which utilize the concepts and teachings of this invention.

I claim:

1. A balancing hoist control system for operating and controlling a balance hoisthaving a pressure-operated member for balancing a load on the hoist, said control system comprising:

an air supply; 1

a pilot-operated regulator valve having a main inlet connected to said air supply, a main outlet connected to said hoist member for supplying said hoist member with a controlled air pressure, and a pilot port adapted to receive a pilot air pressure for controlling the regulator valve and causing it to supply air pressure to said hoist member in response to the pilot air pressure; a control member connected to said pilot port to supply said pilot port with a controlled variable pilot air pressure;

a check valve located between said main inlet in said regulator valve and said air supply and operative to seal said main inlet from said air supply in the event of a drop in pressure in said air supply;

means operative to prevent said regulator valve from exhausting pressure from said main outlet in the event of a substantial drop in pressure in said air supply and the resulting closure of said check valve; and

valve means operative, in response to a substantial drop in pressure of said air supply, to connect said main outlet to said pilot port whereby an operator can use said control member to bleed pressure from said hoist member at a controlled rate to slowly lower a load in the event of the failure of said air supply.

2. The control system of claim 1 wherein:

said means for preventing said regulator valve from exhausting pressure from said main outlet in the event of a substantial drop in pressure in said air supply includes a piston operative, in response to the appearance of a differential pressure across the check valve, to move to a position preventing said regulator valve from exhausting pressure from said main outlet.

3. The control system of claim 2 wherein:

said piston also includes said valve means for connecting said main outlet to said pilot port in response to a substantial drop in pressure of said air supply.

4. The control system of claim 3 wherein:

said regulator valve includes a diaphragm and said piston is operative to engage said diaphragm to prevent it from moving. 

1. A balancing hoist control system for operating and controlling a balance hoist having a pressure-operated member for balancing a load on the hoist, said control system comprising: an air supply; a pilot-operated regulator valve having a main inlet connected to said air supply, a main outlet connected to said hoist member for supplying said hoist member with a controlled air pressure, and a pilot port adapted to receive a pilot air pressure for controlling the regulator valve and causing it to supply air pressure to said hoist member in response to the pilot air pressure; a control member connected to said pilot port to supply said pilot port with a controlled variable pilot air pressure; a check valve located between said main inlet in said regulator valve and said air supply and operative to seal said main inlet from said air supply in the event of a drop in pressure in said air supply; means operative to prevent said regulator valve from exhausting pressure from said main outlet in the event of a substantial drop in pressure in said air supply and the resulting closure of said check valve; and valve means operative, in response to a substantial drop in pressure of said air supply, to connect said main outlet to said pilot port whereby an operator can use said control member to bleed pressure from said hoist member at a controlled rate to slowly lower a load in the event of the failure of said air supply.
 2. The control system of claim 1 wherein: said means for preventing said regulator valve from exhausting pressure from said main outlet in the event of a substantial drop in pressure in said air supply includes a piston operative, in response to the appearance of a differential pressure across the check valve, to move to a position preventing said regulator valve from exhausting pressure from said main outlet.
 3. The control system of claim 2 wherein: said piston also includes said valve means for connecting said main outlet to said pilot port in response to a substantial drop in pressure of said air supply.
 4. The control system of claim 3 wherein: said regulator valve includes a diaphragm and said piston is operative to engage said diaphragm to prevent it from moving. 